Write Tests

Core Principle

Write tests that prove observable behavior through stable public contracts. A good test catches a real regression, survives internal refactors, runs at the right scope, and is simple enough to diagnose when it fails.

Do not optimize for coverage numbers, mock call counts, private methods, snapshots of noise, or tests that only confirm the implementation you just wrote. Use coverage as a gap-finding signal, not as proof that the suite is meaningful.

Workflow

1. Discover local conventions before writing tests:
   • Test framework, command, file naming, fixtures, factories, setup files, CI expectations.
   • Existing tests near the code under change. Prefer the local style when it is sound.